Dosimetry after peptide receptor radionuclide therapy (PRRT) is increasing; however, comparing or pooling of dosimetric results can be challenging since different approaches are used. The aim of this study was to perform a head-to-head comparison of post-PRRT curve fitting and dosimetry obtained from two commercial software Hybrid Viewer Dosimetry and PLANET Dose. Post-therapy imaging included planar scintigraphy at 0.5, 4, 24 and 72 h post-injection of [177Lu]Lu-DOTA-TATE for kinetics and SPECT/CT at 24 h for quantification. On planar imaging, 2 cm regions-of-interest were positioned within the inferior pole of the kidneys and kidney cortex was segmented on low-dose CT. On both planar and SPECT/CT, 2 cm spheres were positioned in the proximal humerus (red marrow equivalent) and in the region with the highest uptake in tumour lesions. TACs were estimated with mono- and bi-exponential fits in both software systems, after which tissue absorbed (kidney, red marrow, tumour) and biological effective doses (kidney) were calculated. Agreement-ICC, Spearman correlation and Bland-Altman plots were used to compare results. Mono-exponential fits showed the most comparable correlation between the measured and fitted data between both software. The ICC between absorbed dose outcomes was > 0.7 in tumour lesions and kidneys, but negative for the red marrow. Spearman correlation was > 0.9 for mono-exponential fits in kidneys and tumour lesions, and −0.7 in red marrow. Bi-exponential fits resulted in lower correlations and agreement values. Concordance between both software packages concerning the number of PRRT cycles with 7.4 GBq was observed based on a biological effective dose limit of 27 Gy to the kidneys. [177Lu]Lu-DOTA-TATE dosimetry results of two software packages were comparable in the same dataset, despite the limited number of imaging time-points. However, these results should be verified in a larger cohort before pooling of clinical data, as the obtained results will depend on acquisition protocol, timing and lesions definition.

中文翻译：

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肽受体放射性核素治疗后，两种用于混合剂量测定的商业软件包之间的正面对比。

肽受体放射性核素治疗（PRRT）后的剂量增加；但是，由于使用了不同的方法，因此比较或合并剂量测定结果可能是一项挑战。这项研究的目的是进行PRRT后曲线拟合和剂量测定的正面对比，该曲线拟合和剂量测定是从两个商业软件Hybrid Viewer剂量测定和PLANET Dose获得的。治疗后成像包括在注射[177Lu] Lu-DOTA-TATE动力学后0.5、4、24和72 h进行平面闪烁显像，并在24 h进行SPECT / CT定量。在平面成像中，将2 cm的感兴趣区域定位在肾脏的下极内，并在低剂量CT上分割肾脏皮质。在平面和SPECT / CT上，均在肱骨近端（等效于红色骨髓）和肿瘤病变吸收率最高的区域中放置2 cm球体。在两种软件系统中，TAC均采用单指数和双指数拟合进行估算，然后计算组织吸收（肾脏，红骨髓，肿瘤）和生物有效剂量（肾脏）。协议-ICC，Spearman相关和Bland-Altman图用于比较结果。单指数拟合显示了两个软件之间的测量数据和拟合数据之间最可比的相关性。肿瘤病变和肾脏吸收剂量结果之间的ICC> 0.7，但红骨髓阴性。对于肾脏和肿瘤病变，单指数拟合的Spearman相关性> 0.9，在红骨髓中为-0.7。双指数拟合导致较低的相关性和一致性值。两个软件包之间关于PRRT循环数的一致性为7。根据对肾脏的27 Gy生物学有效剂量限制，观察到4 GBq。尽管成像时间点数量有限，但两个软件包的[177Lu] Lu-DOTA-TATE剂量测定结果在同一数据集中是可比较的。但是，在汇总临床数据之前，应在更大的队列中对这些结果进行验证，因为获得的结果将取决于采集协议，时间安排和病变定义。